LAUSR

Complex synthesis process, low utilization, and single function have seriously hindered the development of fungicides in resistance to rice sheath blight. Here, an inexpensive and multifunctional Cu(II)-based water-dispersible humic acid (Cu-WH) fungicide with growth-promoting ability was developed with a simple method. A 3 D molybdate carbon hierarchical nanosphere (MoO2-C-HN) catalyst was successfully synthesized using a green route and applied in a solid-phase activation of lignite to obtain water-dispersible humic acid. Cu(II)-based water-dispersible humic acid (Cu-WH) was then formed through a simple reaction of Cu(II) and the humic acid. The resultant Cu-WH showed strong antifungal performance against Rhizoctonia solani in laboratory incubation experiments. After being treated with Cu3-WH (0.1 mg L-1), the control efficiency of rice sheath blight at 1, 3, and 5 days after infection was 90.54%, 78.96%, 66.31%, respectively. It also enhanced the water-holding capacity of substrate and thus effectively improved the growth of rice seedlings. In comparison to commercial rice seedling substrate, the substrate treated with 8 wt% of Cu3-WH increased plant height, stem diameter, fresh weight and chlorophyll content by 19.23%, 35.91%,14.52%, and 42.85%, respectively. The newly developed Cu-WH thus can be used as a novel low-cost efficient fungicide and growth stimulator to treat rice sheath blight as well as to increase rice production.